The effects of NA872 on pulmonary maturation in the fetal lamb and rabbit.

The effect of fetal administration of NA872, metabolite VIII of Bisolvon, on the lecithin/sphingomyelin (L/S) ratio of ovine tracheal fluid and of its administration to the pregnant doe on the fetal rabbit pulmonary pressure-volume relationship was determined. Intravenous administration of NA872 in the long-term cannulated lamb fetus in a dose of 4 mg. per day from either 120 to 125 or 125 to 130 days of gestation produced a significant increase in the L/S ratio. Administration of 4 mg. per kilogram per day to the pregnant doe on days 21 to 24 of gestation resulted in significant enhancement of lung maturation in the 25 day fetal rabbit lung as judged from the pressure-volume relationship; a smaller dose, or the same total dose given over shorter time periods, had no significant effect in the 25 day rabbit fetus. Similarly, 8 mg. per kilogram given to the doe on days 26 and 27 produced no over-all significant effect on the 28 day rabbit fetus, although a seasonal effect was found at this age.